L.O.
You'll think it's silly until you try it. My son went through the exact thing starting about 2 1/2, and his Godmother(I always say to her she's his "Fairy Godmother" cause she's freaking magic!) had me make him a "milkshare" of pureed banana in WHOLE MILK after I sobbed on the phone with her for hours about this very thing.
I sometimes add other fruits and carnation vanilla instant breakfast powder, or Ovaltine to it before blending(I have a magic bullet blender, and it makes whipping up kiddie shakes fast and easy).
It's a recipe for growing pains, and man, does it ever ease his pains. He has one with breakfast, and one for lunch. It's a calcium/potassium punch to growing bones and muscles/tendons/ligaments. You can also make it into a fun smoothie by adding her fave fruits to it. For lunch, you can add a scoop of vanilla ice cream to it to make it a special treat. Whenever he starts having pains, I start making milkshakes. I only wish I had known this when my brother was little. His growing pains were so horrible, my mother, father, me, and my sister(two years older than him) all took turns rubbing his legs for weeks on end, then they'd poof for a bit only to return more vicious than ever.
I also found it very good for mommy fatigue too(we need a super duper energy boost too, as SuperMommies like us get Super tired at times from being...well, Super!) I add two scoops Designer Whey protein powder instead of Ovaltine for my shakes. It's also a very healthy energizing meal replacement for when you need to eat, just don't feel like it. It's also a sneaky healthy way to give them something good, and a bonding experience too! My son gets to load his shake cup, I put on the lid and set the blender cup properly, and he pushes it down to make his milkshakes. Add a fun ring around his cup, and he's all ready to go. Loads of fun, and clean-up is a snap!
Try this first...cheaper than a doctor if it is just growing pains. You'll see a difference in two days. Let us know how she's doing!